Sign Hill Park is South San Francisco’s last undeveloped refuge
  and the home of two endangered butterflies, the mission blue
  butterfly and the callippe silverspot butterfly, as well as a
  variety of rare wildflowers. For many years, the park suffered
  from habitat degradation, reduced funding, and a lack of public
  interest. 
  Efforts to reverse this decades-long trend took off in 2018 when
  the city’s Parks and Recreation Department staff applied for and
  received a Measure K grant from San Mateo County, which awarded
  $75,600 to the city. This critical ecosystem is now thriving, and
  public engagement is strong thanks to an ongoing restoration
  program.